<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <script src="https://cdn.bootcdn.net/ajax/libs/vue/2.6.11/vue.common.dev.js"></script>
</head>

<body>
    <div id="app">
        {{obj}}
        <div v-for="item in arr">
            {{item}}
        </div>
        <button @click="click">aaaa</button>
    </div>
    <script>
        const vm = new Vue({
            el: '#app',
            data: {
                obj: { a: { c: 1 } },
                arr: [1, { a: 1 }]
            },
            mounted() {
                console.log(this.obj);
                this.arr[1].a = 2;
            },
            methods: {
                click() {
                    this.obj.a.c = 2;
                    // this.obj.b = 2;
                    console.log(this.obj);
                }
            }
        })
    </script>
</body>

</html>